A supermolecule-continuum approach with water clusters up to n = 16 H2O molecules has been used to predict the absolute hydration free energies at 298 K (Delta G(hyd)) of both hydrogen (H center dot) and hydride (H-) to be 4.6 +/- 1 and -78 +/- 3 kcal/mol, respectively. These values are combined with a high accuracy prediction of the gas-phase electron affinity (Delta G(gas,298K) = -16.9 kcal/mol) to determine the aqueous electron affinity of H center dot of 99.5 +/- 3 kcal/mol, which yields a reduction potential for H center dot vs SHE of -0.03 +/- 0.15 V. This value is in agreement within 0.2 V with most estimates obtained using a wide variety of approaches. These results can be used to improve the absolute hydricity scale in water which provides additional insights into how a putative hydride interacts with solvent but do not change the ability to predict the relative reactivity of two species using relative hydricity scales.